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The vegetation of three localities of the threatened species Chrysoritis aureus (: )

R.F. TERBLANCHE, T.L. MORGENTHAL and S.S. CILLIERS

Terblanche, R.F., T.L. Morgenthal and S.S. Cilliers. 2003. The vegetation of three local- ities of the threatened butterfly species Chrysoritis aureus (Lepidoptera: Lycaenidae). Koedoe 46(1): 73–90. Pretoria. ISSN 0075-6458. The vegetation and habitat characteristics of three localities of Chrysoritis aureus at the Alice Glockner Nature Reserve, Suikerbosrand Nature Reserve and Malanskraal farm near Heidelberg in , were compared. A numerical classification technique, TWINSPAN, was used and refined by using Braun Blanquet procedures to classify the vegetation at the different localities. A DCA ordination was applied to confirm the results of the classification. Although the general vegetation structure at the three habi- tats of Chrysoritis aureus were found to be similar, marked differences in the floristic composition were evidenced. A different sub-community, compared to the vegetation at Suikerbosrand and Alice Glockner Nature Reserve, was recorded at the Malanskraal habitat of Chrysoritis aureus. These differences in floristic composition, but with simi- larities in vegetation structure, indicate the possible importance of fire for the ultimate survival of these in the Rocky Highveld Grassland. The host plant of Chrysoritis aureus, Clutia pulchella, collected at Malanskraal differed markedly and consistently in their morphology, compared to the individuals from the habitats at Suikerbosrand and Alice Glockner Nature Reserve. These differences in the floristic composition of one of the habitats compared to the others, raise research questions con- cerning the butterfly metapopulation structure, since the subpopulations seem to be adapted to slightly different habitat conditions. The variation in the habitat suggests that the “last remaining locality scenario” for other localised butterflies in South Africa, such as Orachrysops niobe, needs to be redressed. Management strategies are addressed while the importance of conserving rare, localised ecosystems are highlighted by the phytosociological study. Key words: myrmecophilous, Lycaenidae, Chrysoritis, Clutia, Crematogaster, habitat, phytosociology, conservation

R.F. Terblanche ([email protected]), T.L. Morgenthal & S.S. Cilliers, School of Environmental Sciences and Development, Private Bag X6001, Univer- sity for CHE, Potchefstroom, 2520 Republic of South Africa.

Introduction tower near the Natal road of Heidelberg in (Pringle et al. 1994). During 1983, The butterfly Chrysoritis aureus—previously Chrysoritis aureus was added to the protect- known as Poecilmitis aureus before the new ed wild list of the former combination was designated by Heath (1997) under Ordinance 12, since the type locality —is considered to be Rare in the Red Data had been the only known area where the but- book of butterflies (Henning & Henning terfly ocurred (De Wet 1987). G.A. Henning 1989) and the updated list of the Red Data found another locality near Greylingstad book of butterfly species (Henning & Hen- (Pringle et al. 1994). Members of the Lepi- ning 1995). C.R. Barrett and F. Coetzee dis- dopterists’ Society of Africa found another covered Chrysoritis aureus on Christmas locality in Suikerbosrand Nature Reserve Day 1959 on a rocky slope below the water (Henning & Henning 1989) after teams of

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Fig. 1 The location of the habitats of Chrysoritis aureus that were studied.

lepidopterists carried out organised exten- limited to the north eastern extreme of the sive exploration in this reserve (Fig. 1). The reserve, even though the Lepidopterists’s colony at Suikerbosrand seems to be limited Society of Africa organised surveys that cov- in numbers (Henning & Henning 1989; Roos ered many different habitats in the reserve & Henning 2000) though the numbers tend (G.A. Henning 1986a, 1986b, 1987). After to remain stable (The word ‘colony’ refers to decades of exploring by a number of lepi- the subpopulations of these butterflies, that dopterists in the hilly areas of Gauteng and is where they actually breed. The adults usu- the adjacent (Table 1), only ally also fly at or close to these restricted five confirmed localities of Chrysoritis areas). In the Suikerbosrand Nature Reserve, aureus were reported. The distribution of the the only recorded habitat of the butterfly is butterfly can be described as patchy and

Table 1 The locality, altitude and geological system present at the confirmed localities of Chrysoritis aureus Locality Province Locality *Altitude (m)Geological Supergroup Alice Glockner NR 8 km S Heidelberg Gauteng 26º34'S, 28º22'E(2628CB) 1690 Witwatersrand Hill N of Greylingstad Mpumalanga 26º44'S, 28º44'E(2628DA) 1810 Malanskraal locality 14 km W Balfour Mpumalanga 26º39'S, 28º26'E(2628CB) 1780 Ventersdorp Suikerbosrand NR Gauteng 26º29'S, 28º18'E(2628AD) 1720 Witwatersrand Type locality at Heidelberg Gauteng 26º29'S, 28º21'E(2628AD) 1600 Witwatersrand * The grid reference reading is from the north western corner of each minute by minute square. **The Malanskraal locality is close to the borderline between the Ventersdorp supergroup and the Witwatersrand Supergroup.

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Chrysoritis aureus is very localised at each of these localities. The three habitats studied each cover approximately 200 m² – 400 m². All the recorded localities of Chrysoritis aureus are situated at sites where formal or informal urban development pose an ever- increasing threat to the habitat. Habitat destruction across the world as the main cause for the extinction of populations of localised butterflies, is well recognised, thereby emphasising the primary importance of habitat conservation (S.F. Henning 1987; Larsen 1995; Kudrna 1995; Munguira 1995; New 1995; Oates 1995; Opler 1995; Pullin et al. 1995; Thomas 1995; Warren 1995). An ongoing comparative study of the Chrysori- tis aureus habitats (vegetation) is therefore imperative to gain knowledge for develop- ing strategies for the conservation of these habitats. A description of the vegetation of the Chrysoritis aureus habitats is needed if management practices such as translocation of butterflies or habitat restoration is consid- Fig. 2. Clutia pulchella ("Heidelberg morpho- ered. Vegetation studies of the habitats of the type"), the host plant of Chrysoritis aureus. threatened Golden Sun Moth in Australia (O’Dwyer & Attiwill 2000), provided essen- tial information for the restoration of its habitat. A vegetation analysis of the then only known habitat of a threatened butterfly, Aloeides dentatis subsp. dentatis, in South 1993; Retief & Herman 1997) (Fig. 2). The Africa, (Deutschländer & Bredenkamp larvae of Chrysoritis aureus are also con- 1999) was very applicable for its conserva- stantly tended by ants of the genus Cremato- tion management. For this study, the vegeta- gaster (Henning 1983). During the day, the tion of three habitats were compared to iden- larvae shelter for protection and only appear tify possible key factors and to detect possi- at night to feed on their host plants (Henning ble differences between these habitats. 1987a). Well developed dorsal nectary This study also forms part of an ongoing organs (Cottrell 1984) or honey glands (Hen- investigation into the reasons why the sub- ning 1983; 1987a) are present on the larvae populations of the butterfly are confined to and the ants are attracted to feed on the secre- such small areas. In South Africa, studies on tions of these organs (Henning 1983, 1987a). myrmecophilous butterflies, such as In the absence of the ants, a fungal infection Chrysoritis aureus, are limited to life histo- occurs in the dorsal nectary organ and the ry descriptions or reporting of information on the host plant and host ant. Some clues larvae often die after a few days (Henning for the confinement of Chrysoritis aureus to 1983) (Fig. 3). Since both the ant and the its habitats can be found in its life history host plant are needed for survival of (Henning 1983). The host plant of the larvae Chrysoritis aureus at any locality, the habitat is the small shrub Clutia pulchella L. Sens. requirements are complicated. These include lat. (Euphorbiaceae) which is widely distrib- specific local vegetation communities. We uted in South Africa (Arnold & De Wet therefore investigated the vegetation, to con-

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frosty winters. According to information obtained from the South African Weather Service, the long-term average annual rain- fall data from nearby weather stations vary considerably between 620-750 mm per annum (South African Weather Service, Pri- vate Bag X097, Pretoria, 0001). Variation in topography, the rock cover and vegetation structure results in different meso- and microclimates. The sites that were investigated are situated in the Grassland Biome (Rutherford & Westfall 1994; Low & Rebelo 1996), the Bankenveld (Acocks 1988) or Rocky High- veld Grassland (Bredenkamp & Van Rooyen 1996).

Fig. 3. The larva of Chrysoritis aureus. The two white structures at the anterior Materials and methods (head) area, are tubercle organs. Note the fungal growth at the posterior end at Sample plots (5 m x 5 m) were placed on the habi- the dorsal nectary organ. Photo: R.F. tats of Chrysoritis aureus. These plots fitted well on Terblanche. the restricted habitats of Chrysoritis aureus at the Alice Glockner Nature Reserve and Malanskraal, while four sample plots were adequate for the habi- tat at Suikerbosrand. Since the range of occurence of Chrysoritis aureus is so small, the samples are tribute to a niche/habitat profile of Chrysori- thought to be representative. A transect of sample tis aureus. plots over the habitat from the summit to the mid- slopes and down to a valley bottom, was surveyed at the Alice Glockner Nature Reserve to compare the vegetation on the slopes close to the habitats with Study area the habitats of Chrysoritis aureus (Fig. 4). The Three localities inhabited by Chrysoritis floristic composition and cover abundance accord- ing to the Braun-Blanquet scale (Mueller-Dombois aureus were studied: one at the Suiker- & Ellenberg 1974) were noted in each plot during bosrand Nature Reserve, one at the Alice surveys on 12 and 13 February 1999. The number of Glockner Nature Reserve near Heidelberg, Clutia pulchella individuals that occurred in each Gauteng and one at the farm Malanskraal sample plot were determined. Plant specimens were (Fig. 1). The habitats of Chrysoritis aureus deposited in the A.P. Goossens Herbarium of the are situated on the south-facing slopes of Potchefstroom University for C.H.E. The height of rocky ridges and hills. The first two habitats trees (Von Breitenbach 1990; Von Breitenbach et al. studied are situated on the quartzites of the 2001) was noted. These species will, therefore, be Wiwatersrand Supergroup while the habitat referred to as trees, even if they are physionomical- ly not regarded as trees. The height classes as at Malanskraal habitat is situated on the described by Edwards (1983) were used. Habitat lavas of the Ventersdorp Supergroup. The features such as slope, aspect and rockiness were landscape is rugged and broken in appear- noted, though not quantitatively measured. Notes on ance, since the Witwatersrand System was the presence of Chrysoritis aureus and other butter- subjected to considerable folding, faulting flies were continuously made by means of direct and erosion in the past (Du Toit 1954). observations on 7 and 13 November, 1998 as well as 12 and 13 February 1999. The local distribution of The study sites are in the summer rainfall Chrysoritis aureus was confirmed by P. Roos and area, with temperate summers and cold G.A. Henning who have visited the localities for a

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Fig. 4. Position of the 5m x 5m sample plots from the summit (AC 14) to the lower valley bot- tom (AC 8, AC 9) of the hill (southern aspect) at Alice Glockner Nature Reserve. The seven plots (AC 1–AC 7) that are inhabited by Chrysoritis aureus were put out horizontally next to each other along the rocky ridge.

number of years (Roos & Henning 2000). The same pulchella individuals that have been mea- procedure was also followed for the breeding sites, sured near or at the habitats of Chrysoritis i.e., where pupae, larvae, and oviposition by the aureus, ranged from 13 cm to more than female were evidenced. The ants associated with 200 cm tall (in more dense vegetation) and Chrysoritis aureus have been identified by Dr. H.G. fits the descriptions of both entities Robertson, South African Museum, Cape Town, 8000. overviewed by Prain (1925). The plant specimens from the localities of Chrysoritis The TWINSPAN classification algorithm (Hill aureus were compared to the material at the 1979a) was used to analyse the floristic data and the National Herbarium. It does not fit Clutia result was refined by using Braun Blanquet proce- monticola of which the leaves are sessile dures by means of the BBPC-suite (Bezuidenhout et (Retief & Herman 1997). The host plant of al. 1996). A DCA ordination was applied (Hill 1979b) to confirm the results of the classification. Chrysoritis aureus was confirmed to be only Clutia pulchella at all the localities. Clutia pulchella constantly showed specific Results and discussion variation from different localities. Individu- als from Malanskraal have more lanceolate leaves, are of a less bluish-green colour and The host plant the upper surface of the leaves are covered Mr. I. Bampton discovered the host plant of with velvety hairs. This is in contrast to the Chrysoritis aureus in January 1976 (Owen- more ovate, more glaucous and much less Johnston 1991). It is sometimes reported to hairy leaves of individuals from the Alice be Clutia galpinii (Owen-Johnston 1991; Glockner Nature Reserve and Suikerbosrand Heath 2001). Clutia galpinii is considered to Nature Reserve. The reasons for these differ- be a synonym of Clutia pulchella (Retief & ences could be due to the different geologi- Herman 1997). The entity Clutia galpinii cal systems where these plants occur. These refers to a relatively smaller plant of 91 cm – morphotypes may be the subject of more 152 cm, whereas Clutia pulchella reaches detailed study on the taxonomic status of the heights up to 244 cm (Prain 1925). Clutia host plant. Larvae of the different localities

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Table 2 uals were present are characterised by the The number of Clutia pulchella counted as well as presence of large rocks and this seems to be the status of Chrysoritis aureus one of the key habitat requirements of the at the plots (5m x 5m) host plant. The factors that can play a role in Plot Number of Status of excluding Chrysoritis aureus from establish- number Clutia pulchella C. aureus ing at sample plots AC 10 and AC 11, are not individuals 1 = present known. However, both sample plots AC 10 0 = absent and AC 11 are situated on the lower mid- AC 1 4 1 slopes compared to the other sites where AC 2 3 1 Clutia pulchella occurs at higher midslopes AC 3 4 1 in the Alice Glockner Nature Reserve AC 4 7 1 (Fig. 4). AC 5 13 1 AC 6 14 1 Another subject for further research is the AC 7 2 1 local distribution and vitality of Clutia pul- AC 8 0 0 chella in the vicinity of Chrysoritis aureus AC 9 0 0 habitats. It was observed that Clutia pulchel- AC 10 5 0 la may have higher densities and seemed to AC 11 4 0 have better vitality (higher plants) in some of AC 12 0 0 AC 13 0 0 the surrounding areas, where no plots were AC 14 2 0 put out, as Chrysoritis aureus was not pre- MK 15 7 1 sent here. A quantitative survey may shed MK 16 8 1 more light on the above observation. MK 17 10 1 SB 18 6 1 SB 19 10 1 Vegetation classification SB 20 8 1 SB 21 13 1 The floristic composition of the plant com- munities identified is represented in a phyto- sociological table (Table 3) and the results of the DCA-ordination (Fig. 5). The phytosoci- ological analysis resulted in the following two communities with their sub-communi- ties and variants: seems to be adapted to feed on these differ- ent morphotypes of Clutia pulchella. 1. Melinis nerviglumis-Aristida trans- The number of Clutia pulchella individuals vaalensis Community at the sample plots where Chrysoritis aureus 1.1. Melinis nerviglumis-Aristida trans- is present varies (2-14 indiv/25m²) with an vaalensis–Eragrostis curvula Sub- average of 7.8 individuals/25m² for all the community habitats combined—that means an average 1.2 Melinis nerviglumis-Aristida trans- of 0.31 Clutia pulchella indiv/m². The local- vaalensis-Loudetia simplex Sub-com- ity at the Alice Glockner Nature Reserve munity showed the lowest average of Clutia pul- 1.2.1. Anthospermum hispidulum Variant chella individuals namely 6.7 indiv/25m². 1.2.2 Digitaria monodactyla Variant Though Chrysoritis aureus was not present 1.3. Melinis nerviglumis-Aristida trans- at sample plots AC 10, AC 11 and AC 14, vaalensis-Englerophytum magalis- host plant individuals were recorded at these montanum Sub-community sites. The number of host plants at sample plots AC 10 and AC 11 (Table 2) seems to be adequate to serve as possible breeding areas. 2. Elionurus muticus-Eragrostis trichopho- All the sites where Clutia pulchella individ- ra Community

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Fig. 5. DCA-ordination of the sample plots at the Alice Glockner Nature Reserve (AC), Malanskraal (MK) and Suikerbosrand Nature Reserve (SBR).

Community description dorp Supergroup (Table 1). It is charac- terised by the absence of Loudetia simplex 1. Melinis nerviglumis - Aristida and the constant high cover-abundance transvaalensis Community values of Eragrostis curvula, Helichrysum nudifolium and the constant presence of This community is found on the south-facing Garuleum pinnatifidum and Tephrosia slopes and on the terraces within the slopes, capensis (Species group B, Table 3). This and includes a representation of all the habi- sub-community is further characterised by a tats of Chrysoritis aureus that were studied. Apart from the terraces, large rocks (often number of plant species with a low constan- exceeding one metre in length) are conspicu- cy which are exclusive to this subcommuni- ous on all the sites. The community is char- ty. These include the forbs Calpurnia acterised and dominated by the grasses Meli- glabrata, Pelargonium sidoides and the nis nerviglumis, Aristida transvaalensis and dwarf shrub Rhus discolor. Three tree Cymbopogon plurinodis (Species group A, species, namely Leucosidea sericea, Buddle- Table 3). Three subcommunities are recog- ja salviifolia and Gymnosporia buxifolia nised: were recorded in this sub-community with a low cover-abundance and constancy. None 1.1 Melinis nerviglumis-Aristida trans- of these tree species exceeded 2 m in height vaalensis -Eragrostis curvula Sub- and therefore the woody layer is represented community only by shrubs lower than 2 m. The Malans- This sub-community occurs on the south- kraal habitat of Chrysoritis aureus is also the facing slopes at Malanskraal on the Venters- exclusive habitat to this sub-community.

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Table 3 A phytosociological table of the surveys done at the Alice Glockner Nature Reserve, Malanskraal and Suikerbosrand

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Table 3 (continued)

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Table 3 (continued)

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Table 3 (continued)

1.2. Melinis nerviglumis-Aristida trans- the sites of all the other communities, but are vaalensis-Loudetia simplex Sub-com- found scattered throughout this community. munity This community can be divided into two variants: This sub-community was recorded on the 1.2.1 Anthospermum hispidulum Variant quartzite slopes of Alice Glockner and Suikerbosrand on the Witwatersrand Super- This variant is recorded from the south- group (Table 1). The diagnostic species facing rocky slopes of the Alice Glockner include the grasses Loudetia simplex, Nature Reserve and the Suikerbosrand Diheteropogon amplectens, Tristachya leu- Nature Reserve. The constant presence of cothrix and the forbs Vernonia staehelinoides Anthospermum hispidulum characterises this and Senecio venosus. (Species group C, Table variant while Clutia pulchella occurs abun- 3). It is interesting to note that the forbs Ver- dantly on most of the sites that were surveyed nonia staehelinoides and Senecio venosus in this community. The bracken fern Pteridi- (Species group C, Table 3) are absent from um aquilinum was only found at the Suiker-

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bosrand habitat (Table 3) which at first shrubs present are Myrsine africana, Ancy- glance gave the Suikerbosrand habitat a dif- lobotrys capensis and Rhus magalismon- ferent appearance. The similarities with the tana. No Chrysoritis aureus occur at this habitats at Alice Glockner Nature Reserve site since the habitat is not suitable. A num- were only revealed after the vegetation clas- ber of other butterflies namely Coeliades sification. Almost no tree species were found forestan, Junonia archesia, Junonia oenone, at all these sites. The woody layer is repre- natalensis and Anthene butleri sented by Canthium gilfillanii, Myrsine subsp. livida showed typical hilltopping africana and Diospyros lyciodes subsp. behaviour at this site. Hilltopping indicates a guerkei (Table 3). These woody species type of territorial behaviour where males of occurred sporadically, had low cover-abun- butterfly species gather at tops of hills, often dance values, and none were taller than 1 m. at midday—individuals will choose a site Chrysoritis aureus occurs on most of these which they will defend by flying after sites, excluding sites AC 10 and AC 11 that “intruders”. No hilltopping of Chrysoritis are present on the lower midslopes (Fig..4). aureus was observed. Of interest is that Chrysoritis lycegenes, a closely related species of Chrysoritis aureus, uses Myrsine africana as host plant (Hen- 2. Elionurus muticus – Eragrostis ning 1983). Chrysoritis lycegenes, however, trichophora Community. is mainly restricted to central Kwa-Zulu This community is found in the valley bot- Natal and the eastern . tom on the southern hillside below the rocky ridges at the Alice Glockner Nature Reserve. 1.2.2 Digitaria monodactyla Variant It is characterised by the diagnostic species namely the grasses Elionurus muticus, Era- This variant was observed on two flat ter- grostis trichophora, Digitaria tri- races on the slopes at Alice Glockner Nature cholaenoides and Heteropogon contortus as Reserve (Fig. 4). The diagnostic species well as the forbs Indigofera comosa and Ver- include the grasses Aristida aequiglumis, nonia oligocephala (Species Group G, Digitaria monodatyla and Schizachyrium Table 3). Very little exposed rocks occur in sanguineum (Table 3, Species Group E). The this area and the plant species cover abun- terraces are narrow and form a mini-plateau, dance is relatively higher than in all the other whereas the huge exposed rocks that occur sample plots. Chrysoritis aureus is absent in elsewhere on the slopes are absent. this community. Chrysoritis aureus does not colonise these flat terraces, and this coincides with the absence of the host plant Clutia pulchella DCA-ordination (Table 2, Table 3). The results of the DCA-ordination (Fig. 4) support the classification of the communities 1.3 Melinis nerviglumis-Aristida trans- identified from the phytosociological table. vaalensis-Englerophytum magalis- The difference between the floristic compo- montanum Sub-community sition of the habitats of Chrysoritis aureus at Malanskraal and those at Suikerbosrand The summit of the ridge at the Alice Glock- Nature Reserve and Alice Glockner Nature ner Nature Reserve is the habitat of this sub- Reserve, is confirmed by the results of the community which is dominated by shrubs DCA ordination – a topographical gradient rather than grasses and forbs. A small patch from the valley bottom to the upper slopes of vegetation, measuring only approximately are reflected by the configuration of the ordi- 10 m x 10 m, which differs physiognomical- nation. The position of the sample plots on ly from the surrounding areas, is present. ordination axis two can be related to the The diagnostic species is the shrub Englero- geology, with habitats on the Ventersdorp phytum magalismontanum. Other dominant Lava Supergroup at the top and habitats on

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the Witwatersrand Supergroup in the middle Most of the sample plots, of which the plant and at the bottom. The discontinuous posi- species composition, geology and topogra- tion of AC 14 on the scatter diagram may phy favour the presence of Chrysoritis partly be due to its location on the summit of aureus, are to the middle-right and top end of a ridge in contrast with all the other sample the scatter diagram. This confirms the impor- plots that are on south-facing slopes. tance of open vegetation on south-facing The Elionurus muticus-Eragrostis tri- rocky upper slopes for the survival of the chophora community is at the left extreme butterfly. along ordination axis 1 of the scatter diagram and the Melinis nerviglumis-Aristida trans- vaalensis community (Community 1.1., 1.2 Discussion and 1.3) to the middle and right of the scat- ter diagram. The Melinis nerviglumis-Aristi- The habitat of Chrysoritis aureus da transvaalensis-Eragrostis curvula sub- community (Community 2) that occurs at Table 4 provides a matrix in which some of Malanskraal is situated at the top right end of the important environmental habitat charac- the DCA scatter diagram and the Melinis teristics that became apparent in this study, nerviglumis-Aristida transvaalensis-Loude- are listed. The altitude at the investigated tia simplex sub-community in the middle. habitats varies between 1690 m–1780 m,

Table 4 A table with specified habitat factors/ observations that apply to a relevé (= 1) or not (= 0). If a num- ber 1 is in bold it indicates that the presence of Chrysoritis aureus coincides with the factor. The pres- ence of Chrysoritis aureus is indicated in the first row of the matrix

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indicating that the butterfly only occurs in a etation studies at the Chrysoritis aureus certain climate regime (Table 2). The butter- habitat at Suikerbosrand could be seen. Bre- fly colonies are only found at locations that denkamp & Theron (1978) described a Pro- are covered with large rocks. These rocks tea caffra–Helichrysum setosum savanna seem to be a habitat requirement for the host community that is also found on rocky steep plant. In addition, steep upper midslopes southern slopes of the Witwatersrand Super- seem to be essential even on the most local group in the Suikerbosrand Nature Reserve. scale (the butterfly does not breed on the ter- A Protea caffra-Clutia pulchella variant was races). Only the cool southern-facing slopes also distinguished by Bredenkamp & Theron are chosen by the colonies of the butterflies (1978). An open tree stratum was observed for reasons which are not yet clear. This in this variant consisting of a number of trees small-scale study showed that Chrysoritis of which Protea caffra was the most con- aureus is indeed specific on a very local spicuous (Bredenkamp & Theron 1978). No scale with regard to its choice of habitat. Chrysoritis aureus were found in the past (including surveys by members of the Lepi- Two related sub-communities with different dopterists’ Society) in the vegetation where floristic compositions, but similar vegetation Protea caffra individuals are an important structures were recorded as habitats of component of the vegetation. The absence of Chrysoritis aureus. The habitats of Chrysori- Protea caffra and any tree layer at all the tis aureus are dominated by grass species sites where Chrysoritis aureus occur is though a high forb diversity was observed. therefore a confirmation of the more open Many of these forbs are perennials that can nature of the vegetation in the habitats of the survive fire. These include Clutia pulchella butterfly. These open patches in the locations (the host plant) as well as nectar plants for where Clutia pulchella occur and which are the adult butterfly, such as Tetraselago wilm- concomitant with an absence of Protea caf- sii (Species-group D; Table 3). Despite dense fra seems to be localised, and perhaps mar- stands of trees or shrubs observed to be ginal. A larger study area should reveal more growing on the same hill of each of the local- information about the significance of the ities studied, the tree component was almost absence of a tree stratum at the sites where absent where Chrysoritis aureus is present. Chrysoritis aureus occurs. Fire may play an Since dense and relatively diverse communi- important role in the regulation of the ties of trees and shrubs are particular to the Chrysoritis aureus habitats. The timing and Rocky Highveld Grassland (Bredenkamp & intensity of fires in the vegetation among the Van Rooyen 1996)—compared to other rocky ridges where Clutia pulchella grow types of grassland—it is believed that the should be continually monitored to promote more open vegetation noted at the habitats of the survival of Chrysoritis aureus. Chrysoritis aureus are important for conser- vation management. Fire and frost are two Frost is also mentioned in literature to play factors that probably play a key role in the an important role in the distribution of the maintenance of a suitable habitat for woody elements in the Rocky Highveld Chrysoritis aureus since both are needed to Grassland, as mentioned by Bredenkamp & maintain the grasslands in these Rocky Van Rooyen (1996). Grassland vegetation in Highveld Grassland areas. the Rocky Highveld Grassland is restricted to exposed cooler sites (Bredenkamp & Van Acocks (1988) interpreted Bankenveld (now Rooyen 1996). All the habitats of Chrysori- included in the Rocky Highveld Grassland) tis aureus are at exposed sites below the as a fire-maintained false grassland which summit of these hills (on the upper slopes). would develop into savanna if fire was Chrysoritis aureus have not been found in excluded. The vegetation of the Suikerbos- any of the kloofs in these areas where large rand Nature Reserve that was studied by numbers of Clutia pulchella were observed, Bredenkamp & Theron (1978, 1980) pro- though unfortunately no sample plots were vides a further context within which the veg- placed there for quantitative comparisons.

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Since Chrysoritis aureus is also associated markedly from individuals from the locali- with an ant species, Crematogaster liengmei, ties at Alice Glockner Nature Reserve and the structure of the vegetation and the role of the Suikerbosrand Nature Reserve. The factors such as fire may be part of the spe- Malanskraal habitat is also on the Venters- cific habitat requirements of the ants. The dorp Supergroup in contrast with the habitats present ant community studies may reveal at the Alice Glockner Nature Reserve and more insight into these habitat requirements, Suikerbosrand Nature Reserve. An hypothe- especially against the background of the veg- sis to be tested is that the genetic make-up of etation analysis provided in this study. the Chrysoritis aureus populations at the The open nature of the vegetation at the three localities are different, since they seem habitats of Chrysoritis aureus has further to be adapted to habitats that differ to some implications for the control of invasive extent. These findings would be valuable for plants in these areas. Cover-abundances of the conservation of Chrysoritis aureus if the Pteridium aquilinum (bracken fern) translocation of the butterfly or restoration of stands at the Chrysoritis aureus habitat at the habitats are considered. Securing corridors Suikerbosrand Nature Reserve should be that link habitats is an aspect that deserves monitored, since the bracken fern can be attention, especially in the sense that these regarded as invasive. This habitat occurs at must include adequate nectar sources. the border fence of the reserve and is regu- The value of a phytosociological survey to larly burnt as part of a fire break. The best support conservation research and manage- method to control bracken, if deemed neces- ment strategies for a threatened butterfly are sary, is by cutting (Marrs et al. 1998). Brack- confirmed by this study and by Deutschlän- en ferns possess a number of underground der & Bredenkamp (1999). The vegetation rhizomes and are well adapted to fire. structure would be an important aspect to Oinonen (1967) found that bracken estab- consider in the management of areas where lished best from spores that are present on Chrysoritis aureus occurs and could even be sites that had been burnt. studied in more detail on a larger scale. Due Another consideration for the management to the open nature of the vegetation and at all the sites is to prevent bush encroach- localised distribution of the habitats of ment and the establishment of any exotic tree Chrysoritis aureus the application of fire- species, since this will clearly destroy the management should be applied with care localised habitats. Continued control of the while bush encroachment, especially of any invasive Acacia mearnsii, which is a tree layer, should be avoided. Alien vegeta- declared invader (with commercial value) tion in these areas should also be monitored (Bromilow 2001; Henderson 2001) at the since the establishment of exotic tree species Alice Glockner Nature Reserve, is impera- will destroy the habitats of Chrysoritis tive since this will save the butterfly habitats aureus. from a possible catastrophe in future. Further research priorities that were identi- fied, include a study of ant communities locally at the habitats of Chrysoritis aureus. Conclusion To study the nectar sources of Chrysoritis The vegetation at the three localities where aureus in more detail a larger study area than Chrysoritis aureus is present, is similar with the one used here, would be needed since it regard to general structure, but there are dif- seems that the butterfly occasionally wan- ferences in species composition on the sub- ders of from its central breeding ground in community level. A remarkable coincidence search of nectar. Larger sample plots in the Malanskraal habitats, being a different (100 m²) and a larger study area should sub-community, is that the Clutia pulchella therefore be included for such studies. For individuals collected there also differ the studies on the optimal density of the host

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plant, aspects other than southern aspects, References should also be included. ACOCKS, J.P.H. 1988. Veld types of South Africa. Memoirs of the botanical Survey of South Africa It is hoped that more and diverse research on No. 57. the rare and localised butterflies of Africa ARNOLD, T.H. & B.C. DE WET (eds). 1993. Plants of Southern Africa: names and distribution. can be continued since it is believed that a Memoirs of the botanical Survey of South Africa holistic approach in the research will lead to No. 62. more discoveries with regard to the intrigued BEZUIDENHOUT, H., H.C. BIGGS & G.J. BREDENKAMP. 1996. A process supported by the utility BBPC habitat requirements of these organisms. It for analysing Braun-Blanquet data on a personal is recommended that the various sites where computor. Koedoe 39(1): 107-112. Chrysoritis aureus occurs, should receive BREDENKAMP, G.J. & G.K. THERON. 1978. A syne- priority for conservation purposes. In the cological account of the Suikerbosrand Nature Reserve I. The phytosociology of the Witwaters- light of the variation in the habitats of rand Geological System. Bothalia 12(3): 513- Chrysoritis aureus encountered during this 529. study, the securing of one habitat for the con- BREDENKAMP, G.J. & G.K. THERON. 1980. A syne- servation of a local habitat-specific butterfly cological account of the Suikerbosrand Nature Reserve II. The phytosociology of the Venters- might be a risk. The implications for butter- dorp Geological System. Bothalia 13(1&2): flies such as Orachrysops niobe (Brenton 199-216. Blue), where only one locality is known, is BREDENKAMP, G.J. & N. VAN ROOYEN. 1996. Rocky Highveld Grassland. In: LOW, A.B. & A.G. that such butterflies might be in a precarious REBELO (eds.). Vegetation of South Africa, situation even if the remaining habitat is con- Lesotho and Swaziland. Pretoria: Department served, since the meta-population dynamics of Environmental Affairs & Tourism. may be limited. BROMILOW, C. 2001. Problem plants of South Africa. Pretoria: Briza. The threat of urbanisation to the conserva- COTTRELL, C.B. 1984. Aphytophagy in butterflies: its relationships to myrmecophily. Zoological tion of the Rocky Highveld Grassland in Journal of the Linnean Society 79: 1-57. general is mentioned by Bredenkamp & Van DEUTSCHLÄNDER, M.S. & C.J. BREDENKAMP. 1999. Rooyen (1996) and it seems to be prophetic Importance of vegetation analysis in the conser- regarding the conservation of Chrysoritis vation management of the endangered butterfly Aloeides dentatis subsp. dentatis (Swierstra) aureus. Rocky Highveld Grassland is poorly (Lepidoptera: Lycaenidae). Koedoe 42(2): 1-12. conserved (Bredenkamp & Van Rooyen DE WET, K. 1987. Die bewaring van die skoenlap- 1996) and if the number and extent of con- pers van die genus Charaxes en van Erikssonia servation areas are considered the develop- acraeina in die Transvaal. Proceedings of the first Lepidoptera conservation Symposium, ment and conservation of the Alice Glockner Roodepoort: Lepidopterists' Society of southern Nature Reserve will prove to be an important Africa: 5-7. asset for biodiversity conservation and eco- DU TOIT, A.C. 1954. The geology of South Africa Edinburgh: Oliver & Boyd. tourism in South Africa. EDWARDS, D. 1983. A broad-scale structural classi- fication of vegetation for practical purposes. Bothalia 14(3): 705-712. Acknowledgements HEATH, A. 1997. A review of African genera of the tribe Aphnaeini (Lepidoptera: Lycaenidae). We wish to thank Henning & Roos CC as well as Metamorphosis: Occasional Supplement No. 2: Michelle Pfab and Marianne Forsyth (Gauteng 1-60. Department of Agriculture, Conservation and Envi- HEATH, A. 2001. New synonymies and taxonomic notes on the genus Chrysoritis Butler (Lepi- ronment) for their professional support and assis- doptera: Lycaenidae). Metamorphosis 12 (3): tance. This research would not have been possible if 85-98. it had not been for the financial support of the Gaut- HENDERSON, L. 2001. Alien weeds and invasive eng Department of Agriculture, Conservation and plants: a complete guide to declared weeds and Environment, via Roos & Henning CC. invaders in South Africa. Cape Town: Agricul-

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